How to lighten or color viewpoint render view?
If you are talking about quick renders background in the viewpoint, it depends on your world settings.

The quick render considering the World setting's parameter as the "background" shading settings. You should be able to change the quick renders background by changing the world's background settings.


  On Cycles :


I'll take cycle's example first. Down below you have Cycle's world settings.
the "Surface" Panel is for the background of the world (which is an Emission shader).

The quick render using this option for background, changing the color of the "Surface" emission shader should do the job.



For example, if I change my "Surface" Emission color to red, my sky / background / environment turns red




  On Internal :


If you work on internal. Then the World setting tab is a bit bigger.
You have the "World" panel for the background's texture, and for your case the "Ambient occlusion" and "Environment lighting" tabs might interest you, to allow the background's light to affect your scene like a sky.





I really invite you to play around with those settings.